Yellow dye developers and transfer systems employing same

ABSTRACT

WHEREIN R represents a hydrogen atom, an alkyl group or an aryl group and X represents an acid anion, provide improved dye hue and reduced color contamination in diffusion transfer systems.   Substituted 3-(dihydroxybenzyl)thiacyanine yellow dye developers having the general formula:

United States Patent Chapman Apr. 4, 1972 [54] YELLOW DYE DEVELOPERS AND TRANSFER SYSTEMS EMPLOYING [2]] App], No.: 92,272

[52] US. Cl. ..96/3, 96/29 D, 96/77,

96/76 C [5 1] Int. Cl. ..G03c 7/00, G03c 5/54, G030 1/48 [58] Field of Search ..96/3, 77, 29 D, 66 T, 137

[56] References Cited UNITED STATES PATENTS 3,248,219 4/1966 Jacobs ..96/66 T Primary Examiner-J. Travis Brown Assistant Examiner-Alfonso T. Suro Pico Att0rney-W. H. J, Kline, J. R. Frederick and H. E. Cole [57] ABSTRACT Substituted 3-(dihydroxybenzyl)thiacyanine yellow dye developers having the general formula:

iQ/ /IJ aryl group and X represents an acid anion, provide improved dye hue and reduced color contamination in diffusion transfer systems.

18 Claims, No Drawings YELLOW DYE DEVELOPERS AND TRANSFER SYSTEMS EMPLOYING SAME This invention relates to the art of photography and, more particularly, to novel dye developers and to their employment in multicolor diffusion transfer systems.

Diffusion transfer color processes have been described in a number of patents, including US. Pat. No. 2,983,606, wherein photographic elements containing silver halide emulsion layers and layers containing diffusible dye developers (dyes having a silver halide developing function) are exposed to record the latent image in the silver halide and then treated with an alkaline processing composition which permeates the emulsion layers and layers containing the dye developers which then develop the latent images to silver images. At the same time, oxidation products of the dye developers are formed in situ with the silver images and which are relatively nondiffusing in the colloid vehicle of the layers.

The nondiffusing character of the oxidized dye developers is apparently due, at least in part, to a decrease in solubility in the alkaline processing liquid, and may also be due to a hardening effect of the oxidized developer upon the colloid vehicles of the layers which retards the diffusion of the xidized dye developers. The residual unoxidized dye developers remaining in the layers in imagewise distribution are transferred by diffusion to a superposed reception element substantially to the exclusion of the silver image and oxidized dye developer to provide a positive dye image.

When an element containing differentially sensitized silver halide emulsion layers is used and subtractively colored dye developers are present in or contiguous to the respective emulsion layers, the dye developers are oxidized and rendered nondiffusing in the developed regions of the layers upon treatment with the processing liquid. The residual dye developer images in the positive regions are transferred by diffusion and in register to the reception element to provide a multicolor reproduction.

Such systems may be used to produce positive images in a single color or in multicolors. In a three-color system, each silver halide emulsion layer has associated therewith a dye developer possessing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion, i.e., the blue-sensitive silver halide emulsion layer will have a yellow dye developer associated therewith, the green-sensitive silver halide emulsion layer will have a magenta dye developer associated therewith, and the red-sensitive silver halide emulsion layer will have a cyan dye developer associated therewith. The dye developer associated with each silver halide emulsion layer is contained either in a silver halide emulsion layer itself or in a layer contiguous to the silver halide emulsion layer, typically under the silver halide layer with respect to the exposure direction.

As mentioned hereinabove, the yellow dye developer would be normally associated with a blue-sensitive silver halide emulsion for use in a three-color system, although it could actually be associated with any light-sensitive silver halide emulsion to obtain, e.g., monochrome images, false color images, etc. The spectral absorption range for a yellow dye developer should be high in the blue region of the spectrum and low in the red and green regions in order to have as little color contamination as possible in the resulting prints. It would be highly desirable to provide a yellow dye developer that is capable of yielding increased absorption in the blue region, while at the same time providing less absorption in the green region as compared with dye developers previously employed.

Accordingly, it is an object of the present invention to provide novel yellow dye developers suitable for use in a multicolor diffusion transfer system that are capable of yielding prints having an improved dye hue and reduced color contamination.

A further object of the present invention is to provide a novel color diffusion transfer system wherein transfer images have increased absorption in the blue region of the spectrum and much less absorption in the green region.

These and other objects are achieved in accordance with the present invention with the novel yellow photographic dye developers 3-(dihydroxybenzyl)thiacyanine dye developers. It has been found that the dye developers of the present invention possess a spectral absorption range having high absorption in the blue region of the spectrum, while at the same time providing very little absorption in the green region as compared with yellow dye developers of the prior art. Thus, much less color contamination results if the dye developers of the present invention are employed in a diffusion transfer system.

Typical yellow dye developers of the present invention can be characterized by the general formula:

/S S CH= N t...

wherein R represents a hydrogen atom, an alkyl group, an aryl group, and X represents an acid anion.

Representative R groups include an alkyl group, preferably a lower alkyl group, i.e., having from one to four carbon atoms in the chain, particularly methyl and ethyl; and an aryl group,

e.g., phenyl, etc. Furthermore, substituted alkyl groups are intended to come within the meaning of alkyl. Preferably, the substituted alkyl groups are substituted lower alkyl groups containing from one to four carbon atoms in the chain, such as an aralkyl group, e.g., benzyl, phenethyl, etc., a hydroxyalkyl group, e.g., B-methoxyethyl, etc., a carboxyalkyl group, e.g., B-carboxyethyl, etc., a sulfoalkyl group, e. g., w-sulfobutyl, etc. Likewise, substituted arylalkyl groups are intended to come within the meaning of the term alkyl. A preferred substituted arylalkyl group is a 2,5-dihydroxy benzyl group. Preferably, R represents an ethyl group or a 2,5-dihydroxy benzyl group.

X represents an acid anion, e.g., chloride, bromide, iodide, thiocyanate, sulfamate, perchlorate, p-toluenesulfonate, methyl sulfate, ethyl sulfate, etc.

Examples of dye developers coming within the scope of the above formula include:

3,3'-Bis(2,5-dihydroxybenzyl)thiacyanine perchlorate,

3-(2,5-dihydroxybenzyl)-3-ethylthiacyanine perchlorate,

3-( 2,5-dihydroxybenzyl )-3 '-methylthiacyanine perchlorate,

3-(2,5-dihydroxybenzyl)-3'-phenylthiacyanine perchlorate and 3-(2,5-dihydroxybenzyl)-3-propylthiacyanine perchlorate.

A particularly preferred embodiment of the present invention involves the provision of a photographic film unit which is adapted to be processed by passing the unit between a pair of juxtaposed pressure-applying members comprising:

a. a photosensitive element comprising a support having thereon a silver halide emulsion layer having associated therewith a 3-(dihydroxybenzyl)thiacyanine dye developer;

b. a dye image-receiving layer; and

c. a rupturable container containing an alkaline processing composition,

said rupturable container being adapted to be positioned during processing of said film unit so that a compressive force applied to the container by the pressure-applying members will effect a discharge of the containers contents into the film unit.

The dye image-receiving layer of the film unit can be located on a separate support adapted to be superposed on the photosensitive element after exposure thereof. Such imagereceiving elements are disclosed for example, in U.S. Pat. No. 3,362,819. The rupturable container is usually positioned during processing of said film unit so that a compressive force applied to the container by pressure-applying members in a camera will effect a discharge of the containers contents between the image-receiving element and the outermost layer of the photosensitive element. The dye image-receiving layer can also be located integral with the photosensitive element between the support and the lowermost photosensitive silver halide emulsion layer. Such integral receiver-negative photosensitive elements are disclosed, for example, in U.S. Pat. No. 3,415,644 and are useful in camera apparatus of the type disclosed in Belgian Pat. Nos. 718,553 and 718,554. The processing composition for such integral elements wherein the receiver is permanently laminated to the negative contain opacifying agents such as titanium dioxide or carbon black. Barrier layers such as those described in Becker, U.S. Pat. No. 3,384,483, may be used to advantage in such integral elements between the various emulsion and dye developer layers.

The color film assembly of the present invention may contain various silver halide emulsion layers disposed in the usual order, i.e., the blue-sensitive silver halide emulsion layer first with respect to the exposure side, followed by the green-sensitive and red-sensitive silver halide emulsion layers. If desired, a yellow dye layer or a Carey Lea silver layer may be present between the blue-sensitive silver halide emulsion layer for absorbing or filtering blue radiation that may be transmitted through the blue-sensitive layer. If desired, the selectively sensitized silver halide emulsion layers may be disposed in a different order, e.g., the red-sensitive layer first with respect to the exposure side, followed by the green-sensitive and bluesensitive layers.

My novel yellow dye developers may be employed in combination with any suitable magenta dye developer and cyan dye developer in a three-color photosensitive element of the invention. Dye developers, i.e., compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function, and their functioning in color diffusion transfer systems in general are well-known in the art as shown, for example, by U.S. Pat. Nos. 2,983,606; 2,992,106: 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; and 3,142,565.

An alkaline processing or activating composition is conveniently employed in a rupturable container or pod of the film assembly of the present invention. After exposure of the element, the alkaline processing composition is released from the pod to permeate the emulsion layers and initiate development of the latent images contained therein. The dye developers are immobilized in exposed areas as a consequence of the development of the latent images. This immobilization is due, at least in part, to a change in the solubility characteristics of the dye developers upon oxidation. In unexposed areas of the emulsion layers, the dye developers remain diffusible and thus provide imagewise distributions of unoxidized dye developer dissolved in the liquid processing composition as a function of the point-to-point degree of exposure of the silver halide emulsion layers. At least part of these imagewise distributions of unoxidized dye developer are transferred, by diffusion, to the image-receiving layer. The image-receiving layer contains materials adapted to mordant or otherwise fix the diffused, unoxidized dye developers.

Good results are obtained when the dye developers are employed in separate layers contiguous to each silver halide emulsion layer. Such layers can be applied by using coating solutions containing about 0.5 to about 8%, by weight, of the dye developer distributed in a hydrophilic film-forming natural material or synthetic polymer such as gelatin, polyvinyl alcohol, etc., which is adapted to be permeated by aqueous alkaline processing composition.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric or colloidal matrix such as ball-milling and the like techniques, the preparation of a dye developer dispersion can also be obtained by dissolving the dye developer in an appropriate solvent or mixture of solvents, dispersing the resultant solution in the polymeric binder, with optional subsequent removal of the solvent or solvents employed. Further details concerning these dispersing techniques and the solvents employed are found, for example, in U.S. Pat Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

In a color film unit according to the invention, each silver halide emulsion layer containing a dye developer or having the dye developer present in a contiguous layer may be separated from the other silver halide emulsion layers in the film unit by materials including gelatin, calcium alginate, or any of those disclosed in U.S. Pat. No. 3,384,483, polymeric materials such as polyvinylamides as disclosed in U.S. Pat. No. 3,421,892, or any of those disclosed in U.S. Pat. Nos. 2,992,104; 3,043,692; 3,044,873; 3,061,428; 3,069,263; 3,069,264; 3,121,011; and 3,427,158.

Generally speaking, the silver halide emulsion layers in the invention comprise photosensitive silver halide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye developers are dispersed in an aqueous alkaline solutionpermeable polymeric binder, such as gelatin, as a separate layer about 1 to 7 microns in thickness; and the alkaline solution-permeable polymeric interlayers, e.g., gelatin, are about 1 to 5 microns in thickness. Of course, these thicknesses are approximate only and can be modified according to the product desired.

Use of a polymeric acid layer, as disclosed in U.S. Pat. No. 3,362,819, in the film unit of the present invention will enhance the results obtained. Generally, the polymeric acid layer will effect a reduction in the pH of the image layer from about 13 or 14 to at least 11 and preferably 5-8 within a short time after imbibition Such polymeric acids reduce the pH of the film unit after development to terminate further dye transfer and thus stabilize the dye image. Such polymeric acids comprise polymers containing acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium or potassium, or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide. The polymers can also contain potentially acid-yielding groups such as anhydrides or lactones or other groups which are capable of reacting with cases to capture and retain them. Generally, the most useful polymeric acids contain free carboxyl groups, being insoluble in water in the free acid form and which form water-soluble sodium and/or potassium salts.

The polymeric acid layer is usually about 0.3 to about 1.5 mils in thickness. Although the polymeric acid layer is usually located in the receiver portion of the film unit between the support and the image-receiving layer, it can also be located in the negative portion of the film unit, as disclosed in U.S. Pat. No. 3,362,821.

An inert timing or spacer layer coated over the polymeric acid layer may also be used to time" or control the pH reduction of the film unit as a function of the rate at which the alkali diffuses through the inert spacer layer. Examples of such timing layers include gelatin, polyvinyl alcohol or any of those disclosed in U.S. Pat. No. 3,455,686. The timing layer is also effective in evening out the various reaction rates over a wide range of temperatures, e.g., premature pH reduction is prevented when imbibition is effected at temperatures above room temperature, for example, at to F. The timing layer is usually about 0.1 to about 0.7 mil in thickness.

The liquid processing composition that may be employed in this invention is, for example, the conventional aqueous solution of an alkaline material, e.g., sodium hydroxide, sodium carbonate or an amine such as diethylamine, preferably possessing a pH in excess of 12. The composition also preferably contains a viscosity-increasing compound such as a highmolecular-weight polymer, e.g., a water-soluble ether inert to alkaline solutions such as hydroxyethyl cellulose or alkali metal salts of carboxymethyl cellulose such as sodium carboxymethyl cellulose. A concentration of viscosity-increasing compound of about 1 to about 5% by weight of the processing composition is preferred which will impart thereto a viscosity of about 100 c.p.s. to about 200,000 c.p.s.

Development of a diffusion transfer element of the invention may also be effected in the presence of an onium compound, particularly a quaternary ammonium compound, such as disclosed in U.S. Pat Nos. 3,146,102, 3,253,915 and 3,173,786.

The silver halide emulsions used with this invention can comprise silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions may be al., or fine-grain and can be prepared by any of the well-known procedures, e.g., single-jet emulsions, double-jet emulsions, such as Lippmann emulsions, ammoniacal al., thiocyanate or thioether ripened emulsions such as those described in Nietz et al., U.S. Pat. al., 2,222,264; lllingsworth, U.S. Pat. No. 3,320,069; and McBride, U.S. Pat. No. 3,271,157. Surface image emulsions can be used or internal image emulsions can be used such as those described in Davey et al., U.S. Pat. No. 2,592,250; Porter et al. U.S. Pat. No. 3,206,313; and Bacon et al., U.S. Pat. No. 3,447,927. The emulsions may be regular-grain emulsions such as the type described in Klein and Moisar, J. Phot. Sci., Vol. 12, No. 5, Sept/Oct, 1964, pp. 242-251. If desired, mixtures of surface and integral image emulsions can be used as described in Luckey et al., U.S. Pat. No. 2,996,382.

Negative-type emulsions can be used or direct-positive emulsions can be used such as those described in Leermakers, U.S. Pat. No. 2,184,013; Kendall et al., U.S. Pat. No. 2,541,472; Berriman, U.S. Pat. No. 3,367,778; Schouwenaars, British Pat. No. 723,019; lllingsworth et al., French Pat. No. 1,520,821; lves, U.S. Pat. No. 2,563,785; Knott et al., U.S. Pat. No. 2,456,953; and Land, U.S. Pat. No. 2,861,885.

The silver halide emulsions may be unwashed or washed to remove soluble salts. In the latter case, the soluble salts may be removed by chill-setting and leaching or the emulsion may be coagulation-washed, e.g., by the procedures described in Hewitson et al., U.S. Pat. No. 2,618,556; Yutzy et al., U.S. Pat. No. 2,614,928; Yackel, U.S. Pat. No. 2,565,418; Hart et al., U.S. Pat. No. 3,241,969; and Waller et al., U.S. Pat. No. 2,489,341.

Also, the silver halide emulsions may contain speed-increasing compounds such as polyalkylene glycols, cationic surface active agents and thioethers or combinations of these as described in Piper, U.S. Pat. No. 2,886,437; Dann et al., U.S. Pat. No. 3,046,134; Carroll et al., U.S. Pat. No. 2,944,900; and Goffe, U.S. Pat. No. 3,294,540.

Likewise, the silver halide emulsions can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers each used along or in combination include thiazolium salts described in Brooker et al., U.S. Pat. No. 2,131,038, and Allen et al., U.S. Pat. No. 2,694,716; the azaindenes described in Piper, U.S. Pat. No. 2,886,437, and Heimbach et al., US. Pat. No. 2,444,605; the mercury salts as described in Allen et al., U.S. Pat. No. 2,728,663; the urazoles described in Anderson et al., U.S. Pat. No. 3,287,135; the sulfocatechols described in Kennard et al., U.S. Pat. No. 3,236,652; the oximes described in Carroll et al., British Pat. No. 623,448; nitron; nitroindazoles; the mercaptotetrazoles described in Kendall et al., U.S. Pat. No. 2,403,927, Kennard et al., U.S. Pat. No. 3,266,987, and Luckey et al., U.S. Pat. No. 3,397,987; the polyvalent metal salts described in Jones U.S. Pat. No. 2,839,405; the thiuronium salts described in l-lerz et al., U.S. Pat. No. 3,220,839; the palladium, platinum and gold salts described in Trivelli et al., U.S. Pat. No. 2,566,263, and Yutzy et al., U.S. Pat. No. 2,597,915.

Any suitable material can be employed as the image-receiving layer in this invention as long as the desired function of mordanting or otherwise fixingthe dye developer images will be obtained.

Suitable image-receiving materials include N-methox ymethyl polyhexylmethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate; gelatin; and other materials of a similar nature. Polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine as disclosed in U.S. Pat. No. 3,148,061 can also be employed in the invention with good results. Generally, the image-receiving layer is from about 0.25 to about 0.04 mil in thickness. This thickness, of course, may be modified depending upon the result desired. The image-receiving layer may also contain ultraviolet-absorbing materials to protect the mordanted dye images from fading due to ultraviolet light.

The layers of the photographic element employed and described herein may be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film, and related films or resinous materials, as well as glass, paper, metal and the like. Typically, a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alpha-olefin containing two to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like.

The photographic elements of this invention can contain incorporated developing agents such as hydroquinones, catechols, aminophenols, 3-pyrazolidones, ascorbic acid and its derivatives, reductones and phenylenediamines. Combinations of developing agents can be employed in the practice of the invention. The developing agents can be in a silver halide emulsion and/or in another suitable location in the photographic element. The developingagents may be added from suitable solvents or in the form of dispersions as described in Yackel, U.S. Pat. No. 2,592,368, and Dunn et al., French Pat. No. 1,505,778.

The photographic emulsions and elements described in the practice of the present invention may contain various colloids alone or in combination as vehicles, binding agents and various layers. Suitable hydrophilic materials include both naturally occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like, and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers and other layers of the present photographic elements of this invention may also contain alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in US, Pat. Nos. 3,142,568 by Nottorf issued July 28, 1964, 3,193,386 by White issued July 6, 1965, 3,062,674 by Houck et al. issued Nov. 6, 1962, 3,220,844 by l-louck et al. issued Nov. 30, 1965, 3,287,289 by Ream et al. issued Nov. 22, 1966, and 3,411,911 by Dykstra issued Nov. 19, 1968. Particularly effective are those water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing, and those having recurring sulfobetaine units as described in Canadian Pat. No. 774,054 by Dykstra.

The various photographic layers may contain plasticizers and lubricants such as polyalcohols, e.g., glycerin and diols of the type described in Milton et al., U.S. Pat. No. 2,960,404; fatty acids or esters such as those described in Robijns, U.S. Pat. No. 2,588,765, and Duane, U.S. Pat. No. 3,121,060, and silicone resins such as those described in DuPont, British Pat. No. 955,061.

The photographic layers used in the practice of this invention can be coated by various coating procedures including dip coating, air knife coating, curtain coating or extrusion coating using hoppers of the type described in Beguin, U.S. Pat. No. 2,681,294. If desired, two or more layers may be coated simultaneously by the procedures described in Russell,

US. Pat. No. 2,761,791, and Wynn, British Pat. No. 837,095.

This invention also can be used for silver halide layers coated by vacuum evaporation as described in British Pat. No. 968,453 and Luvalle et al., U.S. Pat. No. 3,219,451.

The photographic and other hardenable layers used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed-function hardeners and polymeric hardeners such as oxidized polysaccharides, like dialdehyde starch and oxyguargum and the like.

The following examples further illustrate the novel yellow dye developers of the invention:

EXAMPLE 1 The compound 2-methylbenzothiazole in the amount of 4.5 grams is mixed with 8.6 grams of 2,5-diacetoxybenzyl bromide and the mixture is heated on a steam bath overnight. The 2,5- diacetoxybenzyl bromide is produced in the manner described by D. L. Fields, J. B. Miller and D. D. Reynolds, .l. Orgn. Chem., Vol. 29, page 2,640 (1964). The crude product is triturated with ether and isolated by suction filtration. Five grams of the thus-formed diacetoxybenzyl quaternary salt are refluxed in 30 milliliters of acetic anhydride along with 5 grams of 3-ethyl-2-phenylthiobenzothiazolium iodide for a period of minutes. The solid which separates upon cooling is converted to the perchlorate salt by dissolving it in methanol and adding sodium perchlorate. The diacetoxybenzyl perchlorate salt is then dissolved in 500 milliliters of methanol and hydrolyzed to the dihydroxybenzyl-perchlorate salt by adding 100 milliliters of methanol (saturated with l-lCl) and refluxing for 25 minutes. The yellow dye developer, 3-(2,5- dihydroxybenzyl)-3'-ethylthiacyanine perchlorate, is obtained by suction filtration of the above methanol solution; m.p. 245-247 C.

EXAMPLE 2 Four grams of the diacetoxybenzyl quaternary salt prepared in the manner described in Example 1 and 1 gram of N- nitrosodiphenylamine are heated together in 30 milliliters of acetic anhydride on a steam bath for a period of 2 hours. The reaction mixture is filtered and the filtrate is poured into an aqueous sodium perchlorate solution. The diacetoxybenzyl thiacyanine perchlorate dye is recovered by adding ether to the aqueous sodium perchlorate solution. The acetyl protecting groups are removed by hydrolysis in a methanol-l-lCl solution as described in Example 1. The hydrolysis mixture is concentrated on a rotary evaporator and then diluted with ether. The crude product is dissolved in dimethylformamide and precipitated again by pouring into an aqueous sodium perchlorate solution; yield 1.1 g., Amax 425 nm.

EXAMPLE 3 Blue-sensitive photosensitive elements are prepared by coating a gelatin-subbed film support comprising cellulose acetate with suitable hardened gelatin layers as follows:

1. Yellow Dye Developer Layer The yellow dye developer, 3,3-Bis(2,5-dihydroxybenzyl)thiacyanine perchlorate, is dissolved in a mixture of tricresyl phosphate, ethyl acetate and l-methyl-2-pyrrolidinone and is dispersed in an aqueous gelating solution with a sodium alkylnaphthalene sulfonate dispersing agent. The mixture is dispersed thoroughly with a Waring Blender, coated on the film support and dried to volatilize the ethyl acetate to give a coverage of 20 grams of composition per square foot of support and approximately 50 mg. dye developer per square foot of support.

2. Blue-Sensitive Emulsion Layer A blue-sensitive silver bromoiodide emulsion is then coated at a coverage of mg. of silver and 10 g. of emulsion per square foot of support.

An additional blue-sensitive element is prepared in the foregoing manner with the exception that the novel yellow dye developer of Example 1 is substituted for the novel yellow dye developer, 3,3-Bis(2,5-dihydroxybenzyl)thiacyanine perchlorate, at the same coverages.

A dye image-receiving element is prepared by coating the following layer on a polyethylene-coated paper support:

an image-receiving layer of poly(4-vinylpyridine) (300 mg./ft.") and gelatin (300 mg./ft.'*').

The multilayer photosensitive elements are exposed for 1 second with a 500-watt reflector photoflood at a distance of 13 inches through a mask and processed with 5 grams of a processing solution disposed in a processing pod and having the following composition:

l-methyl-Z-pyrrolidinone 200 ml. lN sodium hydroxide 800 ml. hydroxyethyl cellulose 19.4 g. potassium iodide 2.0 g. Phenidone 1.0 g.

The exposed elements are processed at a gap of 0.0040 inch for a period of 60 seconds at about 20 C. between a pair of pressure rollers in order to spread the processing solution between the exposed elements and receiving elements. After 2 minutes at about 20 C., the film units are separated and the respective image-receiving elements are bathed in a 1% acetic acid solution. A well-defined differential transfer of yellow dye with minimum background density is observed on both image-receiving elements.

The invention has been described with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

1 claim:

1. A photosensitive element comprising a support coated with a silver halide emulsion layer having associated therewith a 3-(dihydroxybenzyl)thiacyanine dye developer.

2. A photosensitive element comprising a support having thereon the following layers in sequence:

a. a cyan dye developer layer,

b. a red-sensitive silver halide emulsion layer,

c. a magenta dye developer layer,

d. a green-sensitive silver halide emulsion layer,

e. a yellow dye developer layer comprising a 3-(dihy-droxybenzyl)thiacyanine, and

f. a blue-sensitive silver halide emulsion layer.

3. The photosensitive element of claim 2 wherein said yelwherein R represents a hydrogen atom, an alkyl group or an aryl group and X represents an acid anion.

4. The photosensitive element of claim 3 wherein R is a 2,5- dihydroxybenzyl group.

5. The photosensitive element of claim 3 wherein R is an ethyl group.

6. A photographic film unit which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members comprising:

said rupturable container being adapted to be positioned during processing of said film unit so that a compressive force applied to said container by said pressure-applying members will effect a discharge of the containers contents within said film unit.

7. The film unit of claim 6 wherein said dye image-receiving layer is located in said photosensitive element between said support and said silver halide emulsion layer.

8. The film unit of claim 6 wherein said photosensitive element comprises a support having thereon the following layers in sequence:

a. a cyan dye developer layer,

b. a red-sensitive silver halide emulsion layer,

c. a magenta dye developer layer,

d. a green-sensitive silver halide emulsion layer,

e. a yellow dye developer layer comprising a 3-(dihydroxybenzyl)thiacyanine, and

f. a blue-sensitive silver halide emulsion layer.

9. The film unit of claim 8 wherein said dye image-receiving layer is coated on a separate support and is adapted to be superposed on said photosensitive element after exposure thereof.

10. The film unit of claim 9 wherein said rupturable container is so positioned during processing of said film unit that a compressive force applied to said container by said pressureapplying members will effect a discharge of the containers contents between said dye image-receiving layer and the outermost layer of said photosensitive element.

11. The film unit of claim 10 wherein said yellow dye developer has the formula:

wherein R represents a hydrogen atom, an alkyl group or an aryl group, and X represents an acid anion.

12. The film unit of claim 11 wherein R is a 2,5-

dihydrozybenzyl group.

13. The film unit of claim 11 wherein R is an ethyl group.

14. A process for producing a photographic transfer image comprising:

a. imagewise-exposing a photosensitive element comprising a support having thereon a silver halide emulsion layer having associated therewith a 3-(dihydroxybenzyl)thiacyanine dye developer;

b. treating said photosensitive element with an alkaline processing composition to effect development of said exposed silver halide emulsion layer;

0. forming an imagewise distribution of diffusible dye developer as a function of said imagewise exposure of said silver halide emulsion layer; and

d. at least a portion of said imagewise distribution of diffusible dye developer diffusing to a dye image-receiving layer.

15. The process of claim 14 wherein said treatment step (b) is effected by:

a. superposing over the layer outermost from the support of said photosensitive element said dye image-receiving layer coated on a support;

b. positioning a rupturable container containing said alkaline processing composition between said exposed photosensitive element and said dye image-receiving layer; and

c. applying a compressive force to said container to effect a discharge of the containers contents between said outer most layer of said exposed photosensitive element and said dye image-receiving layer.

16. The process of claim 15 wherein said dye developer has the formula: 

2. A photosensitive element comprising a support having thereon the following layers in sequence: a. a cyan dye developer layer, b. a red-sensitive silver halide emulsion layer, c. a magenta dye developer layer, d. a green-sensitive silver halide emulsion layer, e. a yellow dye developer layer comprising a 3-(dihy-droxybenzyl)thiacyanine, and f. a blue-sensitive silver halide emulsion layer.
 3. The photosensitive element of claim 2 wherein said yellow dye developer has the formula:
 4. The photosensitive element of claim 3 wherein R is a 2,5-dihydroxybenzyl group.
 5. The photosensitive element of claim 3 wherein R is an ethyl group.
 6. A photographic film unit which is adapted to be processed by passing said unit between a pair of juxtaposed pressure-applying members comprising: a. a photosensitive element comprising a support having thereon a silver halide emulsion layer having associated therewith a 3-(dihydroxybenzyl)thiacyanine dye developer; b. a dye image-receiving layer; and c. a rupturable container containing an alkaline processing composition; said rupturable container being adapted to be positioned during processing of said film unit so that a compressive force applied to said container by said pressure-applying members will effect a discharge of the container''s contents within said film unit.
 7. The film unit of claim 6 wherein said dye image-receiving layer is located in said photosensitive element between said support and said silver halide emulsion layer.
 8. The film unit of claim 6 wherein said photosensitive element comprises a support having thereon the following layers in sequence: a. a cyan dye developer layer, b. a red-sensitive silver halide emulsion layer, c. a magenta dye developer layer, d. a green-sensitive silver halide emulsion layer, e. a yellow dye developer layer comprising a 3-(dihydroxybenzyl)thiacyanine, and f. a blue-sensitive silver halide emulsion layer.
 9. The film unit of claim 8 wherein said dye image-receiving layer is coated on a separate support and is adapted to be superposed on said photosensitive element after exposure thereof.
 10. The film unit of claim 9 wherein said rupturable container is so positioned during processing of said film unit that a compressive force applied to said container by said pressure-applying members will effect a discharge of the container''s contents between said dye image-receiving layer and the outermost layer of said photosensitive element.
 11. The film unit of claim 10 wherein said yellow dye developer has the formula:
 12. The film unit of claim 11 wherein R is a 2,5-dihydrozybenzyl group.
 13. The film unit of claim 11 wherein R is an ethyl group.
 14. A process for producing a photographic transfer image comprising: a. imagewise-exposing a photosensitive element comprising a support having thereon a silver halide emulsion layer having aSsociated therewith a 3-(dihydroxybenzyl)thiacyanine dye developer; b. treating said photosensitive element with an alkaline processing composition to effect development of said exposed silver halide emulsion layer; c. forming an imagewise distribution of diffusible dye developer as a function of said imagewise exposure of said silver halide emulsion layer; and d. at least a portion of said imagewise distribution of diffusible dye developer diffusing to a dye image-receiving layer.
 15. The process of claim 14 wherein said treatment step (b) is effected by: a. superposing over the layer outermost from the support of said photosensitive element said dye image-receiving layer coated on a support; b. positioning a rupturable container containing said alkaline processing composition between said exposed photosensitive element and said dye image-receiving layer; and c. applying a compressive force to said container to effect a discharge of the container''s contents between said outermost layer of said exposed photosensitive element and said dye image-receiving layer.
 16. The process of claim 15 wherein said dye developer has the formula:
 17. The process of claim 16 wherein R is a 2,5-dihydroxybenzyl group.
 18. The process of claim 17 wherein R is an ethyl group. 